Hydrogen transfer agents for slurry processing of hydrocarbonaceous black oils

ABSTRACT

Asphaltene-containing hydrocarbonaceous black oils are hydrogenated in a slurry process utilizing a hydrogen transfer agent. The transfer agent constitutes a finely divided sponge metal, saturated with hydrogen at elevated pressure, and admixed with the charge stock to form a reactive slurry. Preferred sponge metals include titanium, zirconium, vanadium, tungsten and nickel. In a specific embodiment, the reactive slurry also contains a hydrorefining catalyst of an unsupported sulfide of a Group V-B metal.

United States Patent Inventor Rudolf H. Hausler Rolling Meadows, lll.

Appl. No. 15,666

Filed Mar. 2, 1970 Patented Nov. 23, 1971 Assignee Universal 011Products Company Des Plaines, Ill.

HYDROGEN TRANSFER AGENTS FOR SLURRY PROCESSING OF HYDRQCARBONACEOUS [56]References Cited UNITED STATES PATENTS 3,152,981 10/1964 Berlin et al.208/217 3,182,016 5/1965 Cole et al 208/216 3,366,683 1/1968 Johnson eta1. 252/472 Primary Examiner-Delbert E. Gantz Assistant Examiner-G. .1Crasanakis Attorneys-James R. Hoatson, Jr. and Robert W. EricksonABSTRACT: Asphaltene-containing hydrocarbonaceous black oils arehydrogenated in a slurry process utilizing a hydrogen transfer agent.The transfer agent constitutes a fine- 1y divided sponge metal,saturated with hydrogen at elevated pressure, and admixed with thecharge stock to form a reactive slurry. Preferred sponge metals includetitanium, zirconium, vanadium, tungsten and nickel. in a specificembodiment, the reactive slurry also contains a hydrorefining catalystof an unsupported sulfide of a Group V-B metal.

/6 Catalyst 6 Separation Zone 1 Fractionation System 1 Sponge Metal 6[Separation Zone 1 9 2 Hydrogen Saturation Catalyst Hydrogen Recovery 1g I Catalyst 2 HYDROGEN TRANSFER AGENTS FOR SLURRY PROCESSING OFI-IYDROCARBONACEOUS BLACK OILS APPLICABILITY OF INVENTION The inventiondescribed herein encompasses a procedure for effecting the hydrogenationof hydrocarbonaceous black oils in a slurry-type process utilizing ahydrogen transfer agent. The hydrogen transfer agents, herein sometimesreferred to as sponge metals due to their ability to absorb largevolumes of hydrogen, are finely-divided metals in the elemental state.The heavy oils, to which the present invention is applicable, arecharacterized as containing asphaltenic material and include atmospherictower bottoms, vacuum tower bottoms, crude oil residuals, topped crudeoils, coal oil extracts, crude oils extracted from tar sands, etc.;these are often referred to in the art as black oils."

Black oils contain high molecular weight sulfurous compounds inexceedingly large quantities. In addition, they contain excessivequantities of nitrogenous compounds, high molecular weightorganometallic complexes, principally comprising nickel and vanadium,and asphaltenic material. The asphaltenic material is generally found tobe complexed with, or linked to sulfur, and, to a certain extent, withthe organometallic contaminants. An abundant supply of suchhydrocarbonaceous material exists, most of which has a gravity less than20.0 AP], and which is further characterized by a boiling rangeindicating that 10.0 percent by volume and generally more, boils above atemperature of about l050 F.

Difiiculties encountered in processing black oils, utilizing a fixed-bedof a supported catalyst, have indicated that a more advantageous routeresides in a slurry process wherein an unsupported catalytic componentand hydrogen are admixed with the charge stock. The principal difficultywith a fixed-bed system is the lack of a suitable technique whichaffords the various fixed-bed catalysts sufficient sulfur stability inthe presence of the asphaltenic and organometallic compounds. Not onlydoes the catalyst deactivate rapidly, as a result of the formation ofthe carbon thereon, but the metallic contaminants become deposited uponthe catalyst, steadily increasing in quantity until such time as thecomposition of the catalyst is changed to the extent that undesirableresults are obtained. The asphaltenic fraction consists primarily ofhigh molecular weight, nondistillable coke precursors, insoluble inlight hydrocarbons such as propane, pentane, or heptane. A significantcharacteristic of asphaltenic material is the extremely low hydrogen tocarbon atomic ratio. The hydrogen to carbon atomic ratio of most nativeasphaltenes is less than l.0:l.0. In order to convert this asphaltenicmaterial into lower-boiling hydrocarbon products, it is necessary toincrease the hydrogen to carbon atomic ratio by way of hydrogenation.

The primary purpose of the present invention is to provide an efficientand economical scheme for effecting the hydrogenation ofasphaltene-containing hydrocarbonaceous black oils. My invention isparticularly directed toward the use of hydrogen transfer agents in theform of finely divided sponge metals capable of absorbing large volumesof hydrogen. Although the present application of hydrogen transferagents is specifically directed toward the slurry processing ofhydrocarbonaceous black oils, the technique is well suited for use inother processes in which hydrogenation assumes a dominant role. Suchother processes include, but not by way of limitation, smoke pointimprovement of kerosene fractions, desulfurization, denitrification,aromatic and olefinic saturation, hydrotreating of naphtha fractions,etc.

OBJECTS AND EMBODIMENTS A principal object of my invention is to providea slurry process for hydrogenating an asphaltene'containinghydrocarbonaceous charge stock. A corollary object is to utilize afinely divided sponge metal as a hydrogen transfer agent to efiectintimate dispersion of hydrogen within the charge stock.

Another object of my invention is to improve theoperation of a catalyticslurry process in which the catalyst is an unsupported sulfide of ametal from Group V-B of the Periodic Table.

Therefore, in one embodiment, my invention provides a process forhydrorefining an asphaltene-containing hydrocarbonaceous charge stockwhich comprises saturating a finely divided sponge metal with hydrogenat a pressure greater than about 500 p.s.i.g. and a temperature in therange of about to about 350 C., admixing the hydrogen-saturated spongemetal with said charge stock and reacting the resulting slurry at apressure greater than about 500 p.s.i.g. and a temperature above about350 C.

Other objects and embodiments of my invention, relating to specific andpreferred hydrogen transfer agents, and operating conditions andtechniques, will become apparent from the following detailed summary ofthe invention. For example, another embodiment involves saturating thesponge metal with hydrogen at a pressure in the range of 1,000 to about5,000 p.s.i.g., and reacting the sponge metal/charge stock slurry at atemperature in the range of 350 to about about 500 C. and a pressurefrom about 1,000 to about 5,000 p.s.i.g.

SUMMARY OF INVENTION Previous investigations into the slurry processingof hydrocarbonaceous black oils for hydrogenation and/or hydrorefining,the terms being used synonymously, have indicated that significantproblems and difficulties exist. One principal difficulty involvesbringing the charge stock into simultaneous contact with the hydrogen,or with the unsupported catalyst and hydrogen. When hydrogen is broughtinto the reaction system, whether separate from, or in conjunction withthe charge stock, it tends to coalesce to form large bubbles. Thisproblem is not solved through the use of mechanical feed devices such asspray nozzles, bayonets, high speed mixing valves, etc., since thecoalescing will continue to take place in the initial section of thereaction zone with the result that the actual reaction time becomesseverely limited. The primary purpose of the present invention is toprovide a method whereby a greater quantity of hydrogen is madeavailable for reaction with the charge stock over the entire length ofthe reaction chamber.

As hereinbefore stated, the present invention contemplates thesimultaneous use of the hydrogen transfer agent and unsupported catalystof a sulfide of a Group V-B metal. Slurry processing with unsupportedcatalytic components have indicated that a preferred form is a metallicsulfide, as distinguished from other compounds such as metallic oxides,metallic sulfates, etc. Furthermore, it has been found that the sulfidesof the metals of Group V-B vanadium, niobium and tantalum, yield moreadvantageous results, with a vanadium sulfide being particularlypreferred. Furthermore, the catalytic vanadium sulfide isnonstoichiometric and is produced in situ within the reaction chamber byinitially employing vanadium tetrasulfide in slurry admixture with thecharge stock.

The use of the term unsupported," is intended to connote a catalyst, orcatalytic component which is not an integral part of a composite with arefractory inorganic oxide carrier material. That is, the catalyst is avanadium sulfide without the addition thereto of extraneous material.Although the precise atomic ratio of sulfur to vanadium is not knownwith accuracy, analyses have indicated that the nonstoichiometric,catalytic sulfide has a ratio of sulfur to vanadium not less than 0.8:1,nor greater than 1.821. This is not intended to mean that the vanadiumsulfide has but a single specific sulfur/vanadium atomic ratio, butrather refers to a mixture of vanadium sulfides having nonstoichiometricatomic ratios within the aforesaid range. Although four oxidation statesare known for vanadium, 2, 3, 4 and 5, Periodic Table of the Elements,E. H. Sargent and Company, 1964, only three stoichiometric vanadiumsulfides are sufiiciently stable for identification. These are:monovanadium sulfide, VS; sesquivanadium sulfide V 8 and, pentavanadiumsulfide, V 5 Handbook of Chemistry and Physics, Chemical RubberPublishing Company, 42nd Edition, Page 680, 1960-1961. The literature isreplete with references to many identifiable nonstoichiometric vanadiumsulfides which are specific compounds in their own right, possibly themost common being the tetrasulfide, V8,. It has previously been foundthat the catalytic vanadium sulfide is not identifiable'as any of thestoichiometric vanadium sulfides, or as V8,. The catalytic,nonstoichiometric vanadium sulfide is, however, produced in the reactionzone in situ through the conversion of the tetrasulfide at reactionconditions. It is within the scope of my invention to employ discreteparticles consisting of the hydrogen transfer agent and the sulfide ofthe Group V-B metal.

A wide variety of metals can be utilized as the hydrogen transfer agent,or sponge metal, in accordance with my invention. The metals areemployed in a finely divided state, generally from about 0.05 mm. toabout 3.0 mm., and include magnesium, titanium, zirconium, strontium,barium, hafnium, vanadium, niobium, tantalum, chromium, tungsten,manganese, iron, nickel, and tin. Group VIII noble metals, as well asother metals, are suitable, and may be used to advantage as the hydrogentransfer agent. The generally high cost of these metals, however,precludes their use from an economic standpoint. Of the foregoingmetals, those preferred include titanium, zirconium, vanadium, tungstenand nickel. In accordance with my invention, the finely divided spongemetal, for example titanium, is saturated with hydrogen at a pressuregreater than about 500 p.s.i.g., and preferably from about 1,000 toabout 5,000 p.s.i.g., and at a temperature in the range of about 175 toabout 350 C. The hydrogen-saturated sponge metal is admixed with thehydrocarbonaceous charge stock and the resulting slurry is reacted in anelongated reaction chamber at a pressure greater than about 500 p.s.i.g.and a temperature above about 350 C. A preferred pressure range is from1,000 to about 5,000 p.s.i.g., while the preferred temperature is in therange of about 350 to about 500 C.

The titanium releases its hydrogen, which is evenly distributed therein,within the reactor in a form which facilitates rapid reaction. Since thetitanium particles are sufficiently small, hydrogen diffusion within theparticle is not limiting upon a reaction rate. Similarly, whereconvection within the reaction chamber is similar to that of a fluidizedbed system, hydrogen diffusion within the oil phase is not rate limitingeither, since the titanium particles carry the hydrogen where it isrequired for the reaction. This type of system enhances the advantagesof an upflow slurry operation which is not very efficient when hydrogenis brought into the reaction chamber in a vaporous state. The reason forthis resides in the fact that the titanium powder will be more finelydivided than hydrogen bubbles, and the latter tend to coalesce, whilethe titanium powder will remain finely divided. Titanium, for example,absorbs about 1,500 times its own volume of hydrogen, which is virtuallyequivalent to a pressure of 1,500 atmospheres. The absorption takesplace at temperatures in the range of about l75 to about 350 C., whereasthe release of hydrogen commences at about 350 C., and takes placerather rapidly at 450 C. In order to adjust the temperature at whichhydrogen is absorbed and released, titanium may be alloyed with othermetals, or other metals can be used in and of themselves. Thus, forexample, uranium will decrease the hydrogen release temperature. Whenthe process of the present invention is egfi'ected in conjunction withan unsupported sulfide of a Group V-B metal as a hydrorefining catalyst,the slurry will generally contain about 1.0 to about 25.0 percent byweight of said metal sulfide. The total reaction product effluent isseparated to provide (1) an asphaltenic sludge containing the hydrogentransfer agent and (2) a product stream of normally gaseous and normallyliquid hydrocarbons. The latter may be additionally separated toconcentrate the hydrogen which is then utilized to resaturate thehydrogen transfer agent. Where a catalytic metal sulfide is utilized inconjunction with the hydrogen transfer agent, a series of separationtechniques is effected. Although both the metal sulfide and hydrogentransfer agent may be introduced into the hydrogen saturation zone, apreferred technique involves separation of the hydrogen transfer agentfrom the metal sulfide whereby at least a portion of the latter may beremoved from the process for regeneration and/or metal recovery. Suchseparation may be effected through any of the suitable, commonseparation techniques including floatation, settling, etc.

DESCRIPTION OF A PREFERRED EMBODIMENT The illustration of a preferredembodiment involves the utilization of both a hydrogen transfer agentand a catalytic vanadium sulfide. This type scheme is diagrammaticallypresented in the accompanying drawing as a simplified flow scheme. Inthe drawing, various flow valves, control valves, instrumentation andstartup lines, coolers, pumps and/or compressors, etc., have either beeneliminated, or reduced in number; only those vessels and connectinglines considered necessary for a complete understanding of the presentinvention are shown. The use of such miscellaneous appurtenances arewell within the purview of one having skill in the art of I petroleumprocessing techniques.

The fresh feed charge stock in this illustrative embodiment is a vacuumtower bottoms product having a gravity of 9.8 API, and a 30.0 percentvolumetric distillation temperature of about 1050 F. Contaminatinginfluences include about 5.2 percent by weight of heptane-insolubleasphaltenes, 3.06 percent by weight of sulfur, 4.030 ppm. by weight ofnitrogen and a total metals concentration of about ppm.

With reference now to the drawing, the charge stock enters the processby way of line 1 and is introduced into a lower portion of elongatedreactor 3. Also, introduced into reactor 3, via line 2, is a mixture ofhydrogen-saturated sponge metal and about 4.0 percent by weight ofvanadium sulfide catalyst. The saturation of the sponge metal, titanium,is effected at a temperature of about 300 C. and a pressure of about3,500 p.s.i.g. The temperature at the lower portion of reactor 3 isabout 380 C. and the pressure is slightly less than about 3,500 p.s.i.g.as a result of the normal pressure drop experienced due to fluid flowthrough the system. In view of the fact that the reactions beingeffected are exothermic in nature, the temperature at the outlet ofreactor 3 is about 450 C. The reaction zone effluent is withdrawn by wayof line 4 into catalyst separation zone 5. The catalyst separation zoneis illustrated as a single vessel in order to simplify the flow scheme.In actual practice, for example, a hot flash system, functioning atessentially the same pressure as the reaction chamber in a first stage,and at a slightly reduced pressure in a second stage, serves to separatethe product efiluent into a vaporous phase, the principal portion ofwhich boils below about 800 F. and a liquid phase containing unconvertedasphaltenic material, titanium and the catalytic vanadium sulfide. Thelatter is indicated as emanating from catalyst separation zone 5 by wayof line 7, and introduced therethrough to sponge metal separation zone8. The separated titanium is introduced, by way of line 11, intohydrogen saturation zone 12, wherein the same absorbs hydrogen from line13 at a pressure of about 3,500 and a temperature of about 300 C. Thesubstantially titanium-free stream, from sponge metal separation zone 8,containing unconverted asphaltenes and the vanadium sulfide, is removedby way of line' 9 and recycled to the reaction chamber by way of line 2.Although this stream may be totally recycled to combine with the freshhydrocarbonaceous charge stock, a preferred operating technique involveswithdrawing a drag stream, through line 10, containing at least about10.0 percent by weight of the vanadium sulfide. Any suitable means maybe utilized to separate solid catalyst and unreacted asphaltenicmaterial from the liquid phase hydrocarbons, including filtration,settling tanks, a series of centrifuges, etc. A like quantity of freshvanadium tetrasulfide is then added by way of line 18 in order tomaintain the selected catalyst content of the slurry. The principallyvaporous phase from catalyst separation zone 5 is withdrawn by way ofline 6, and, following its use as heat exchange medium, is introducedthereby into fractionation system 15. It is understood that catalystseparation zone 5 may function to remove all distillable hydrocarbonsboiling below desired temperatures other than 800 F., such temperaturestypically including 750 F., 950 F., 1050 F., etc. With respect tofractionation system 15, one typical separation involves removingbutanes and lowerboiling normally gaseous components as an overheadstream in line 16, pentane, and other normally liquid hydrocarbons areremoved by way of line 17. The illustrated flow diagram also presentsanother technique whereby a normally liquid recycle stream is removedfrom fractionation system by way of line 2, being utilized to facilitatethe transfer of the hydrogen-saturated titanium, from line 14 and theseparated catalytic vanadium sulfide, from line 9, to the lower portionof reaction chamber 3.

Analyses of the normally liquid product effluent, withdrawn fromfractionation system 15 by way of line 17, indicate greater than about98.0 percent heptane-insoluble conversion, less than about 10.0 p.p.m.of organometallic complexes and a gravity of about 18.2 AP].Furthermore, the analyses indicate about 55.0 to about 70.0 percentconversion of sulfurous and nitrogenous compounds into hydrogen sulfide,ammonia and hydrocarbons.

l claim as my invention:

1. A process for hydrorefining an asphaltene-containinghydrocarbonaceous charge stock which comprises saturating a finelydivided sponge metal with hydrogen at a pressure greater than about 500p.s.i.g. and a temperature in the range of about 175 to about 350 C.,said sponge metal being selected from the group consisting of titanium,zirconium, vanadium, tungsten and nickel, admixing the hydrogensaturatedsponge metal with said charge stock and reacting the resulting slurry ata pressure greater than about 500 p.s.i.g. and a temperature above about350 C.

2. The process of claim 1 further characterized in that said spongemetal is hydrogen-saturated at a pressure from 1,000 to about 5,000p.s.i.g., and the resulting slurry is reacted at a temperature in therange of 350 to about 500 C. and a pressure from 1,000 to about 5,000p.s.i.g.

3. The process of claim 1 further characterized in that said spongemetal is titanium.

4. The process of claim 1 further characterized in that said spongemetal is zirconium.

5. The process of claim 1 further characterized in that said spongemetal is vanadium.

6. The process of claim 1 further characterized in that said spongemetal is tungsten.

7. The process of claim 1 further characterized in that said spongemetal is nickel.

8. The process of claim 1 further characterized in that said slurrycontains, as a hydrorefining catalyst, an unsupported sulfide of a GroupV-B metal.

9. The process of claim 8 further characterized in that said Group V-Bmetal sulfide is a vanadium sulfide.

10. The process of claim 8 further characterized in that said slurrycontains from 1.0 percent to about 25.0 percent by weight of said GroupV-B metal sulfide.

11. A process for hydrorefining an asphaltene-containinghydrocarbonaceous charge stock which comprises saturating a finelydivided sponge metal with hydrogen at a pressure greater than about 500p.s.i.g. and a temperature in the range of about to about 350 C.,admixing with the charge stock said hydrogen-saturated sponge metal anda hydrorefining catalyst comprising an unsupported sulfide of a GroupV-B metal, and reacting the resulting slurry at a pressure greater thanabout 500 p.s.i.g. and a temperature above about 350 C.

12. The process of claim 11 further characterized in that 7 said GroupV-B metal sulfide is a vanadium sulfide.

2. The process of claim 1 further characterized in that said spongemetal is hydrogen-saturated at a pressure from 1,000 to about 5,000p.s.i.g., and the resulting slurry is reacted at a temperature in therange of 350* to about 500* C. and a pressure from 1,000 to about 5,000p.s.i.g.
 3. The process of claim 1 further characterized in that saidsponge metal is titanium.
 4. The process of claim 1 furthercharacterized in that said sponge metal is zirconium.
 5. The process ofclaim 1 further characterized in that said sponge metal is vanadium. 6.The process of claim 1 further characterized in that said sponge metalis tungsten.
 7. The process of claim 1 further characterized in thatsaid sponge metal is nickel.
 8. The process of claim 1 furthercharacterized in that said slurry contains, as a hydrorefining catalyst,an unsupported sulfide of a Group V-B metal.
 9. The process of claim 8further characterized in that said Group V-B metal sulfide is a vanadiumsulfide.
 10. The process of claim 8 further characterized in that saidslurry contains from 1.0 to about 25.0 percent by weight of said GroupV-B metal sulfide.
 11. A process for hydrorefining anasphaltene-containing hydrocarbonaceous charge stock which comprisessaturating a finely divided sponge metal with hydrogen at a pressuregreater than about 500 p.s.i.g. and a temperature in the range of about175* to about 350* C., admixing with the charge stock saidhydrogen-saturated sponge metal and a hydrorefining catalyst comprisingan unsupported sulfide of a Group V-B metal, and reacting the resultingslurry at a pressure greater than about 500 p.s.i.g. and a temperatureabove about 350* C.
 12. The process of claim 11 further characterized inthat said Group V-B metal sulfide is a vanadium sulfide.